The present invention relates generally to a method for manufacturing a rotary article, and, more specifically, to a method for manufacturing a rotary article such as impeller by cold metal transfer welding deposition, as well as the rotary article as manufactured.
Rotary articles which have internal passages, such as impellers with a plurality of internal flow passages, are not easy to manufacture by traditional manufacturing techniques such as casting or forging. Impellers are widely used inside pipes or conduits of equipment such as pumps, compressors and gas turbine engines to increase or decrease a pressure and flow of a fluid. For example, an impeller may be used in a centrifugal pump to transfer energy from a motor that drives the pump to the fluid being pumped by accelerating the fluid outwards from the center of rotation. The velocity achieved by the impeller transfers into pressure when the outward movement of the fluid is confined by the pump casing. A typical impeller includes a bore to receive a drive-shaft rotated by a motor or other drive mechanism and vanes having hollow spaces formed in interiors thereof to push the fluid radially, and is hard to manufacture by traditional manufacturing techniques due to its complicated structure.
A conventional method for manufacturing impellers is to divide and mold the impeller as several members and then join the separately molded members together by welding or other such joining methods. However, in comparison with integrally formed impellers, the impellers manufactured by joining separately molded parts of the impeller have relatively weak mechanical properties.
Presently, there is a method in which impellers are manufactured by a process including pre-milling, electrical discharge machining (EDM) roughing and EDM finishing. But the cycle time of this process is usually more than 5 weeks. Moreover, high plant and equipment (P&E) investment is needed for milling center and EDM machine. It is neither efficient nor economic due to the long cycle time and high P&E investment request.
Therefore, it is desired to provide a novel method for manufacturing rotary articles such as impellers on an efficient and economic basis.